ArcObjects -枚举地理数据库中的要素类和数据集

Question

我正在尝试使用vba/arcobjects枚举文件地理数据库的内容(要素类和要素数据集，对表不感兴趣等)。

我已经将文件GDB设置为IGxDatabase对象，但是找不到进一步深入的方法。我已经查看了地理数据库对象模型，并尝试使用IFeatureClass和IFeatureDataset，但似乎都没有返回有用的结果。

提前感谢您的帮助

Answer 1

枚举地理数据库中包含的名称要比枚举名称可以打开的内容快得多。棘手的部分是遍历featuredataset中的名称。虽然IFeatureWorkspace.Open可以用来打开一个特征类，而不需要首先打开包含它的特征数据集，但是在一个特征数据集中获取特征类名需要打开特征数据集。

如果您确定需要打开每个功能类，那么我认为使用IWorkspace.Datasets、IEnumDataset和IDataset而不是IWorkspaceDatasetNames、IEnumDatasetname和IDatasetname没有什么坏处。

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Option Explicit
Sub TestGetContents()
    Dim pGxApp As IGxApplication
    Set pGxApp = Application
    If Not TypeOf pGxApp.SelectedObject Is IGxDatabase Then
        Debug.Print "select a geodb first"
        Exit Sub
    End If
    Dim c As Collection
    Set c = GetContents(pGxApp.SelectedObject)
    Dim l As Long
    For l = 1 To c.Count
        Dim pName As IName
        Set pName = c.Item(l)
        If TypeOf pName Is IFeatureClassName Then
            Dim pFC As IFeatureClass
            Set pFC = pName.Open
            Debug.Print pFC.AliasName, pFC.FeatureCount(Nothing)
        ElseIf TypeOf pName Is IFeatureDatasetName Then
            Dim pDSName As IDatasetName
            Set pDSName = pName
            Debug.Print pDSName.name, "(featuredataset)"
        End If
    Next l
End Sub

Function GetContents(pGxDB As IGxDatabase) As Collection
    Dim c As New Collection
    Dim pEnumDSName As IEnumDatasetName
    Set pEnumDSName = pGxDB.Workspace.DatasetNames(esriDTAny)
    Dim pDSName As IDatasetName
    Set pDSName = pEnumDSName.Next
    Do Until pDSName Is Nothing
        If TypeOf pDSName Is IFeatureClassName Then
            c.Add pDSName
        ElseIf TypeOf pDSName Is IFeatureDatasetName Then
            c.Add pDSName
            AddSubNames pDSName, c
        End If
        Set pDSName = pEnumDSName.Next
    Loop
    Set GetContents = c
End Function

Sub AddSubNames(pDSName1 As IDatasetName, c As Collection)
    Dim pEnumDSName As IEnumDatasetName
    Set pEnumDSName = pDSName1.SubsetNames
    pEnumDSName.Reset
    Dim pDSName2 As IDatasetName
    Set pDSName2 = pEnumDSName.Next
    Do Until pDSName2 Is Nothing
        If TypeOf pDSName2 Is IFeatureClassName Then
            c.Add pDSName2
        End If
        Set pDSName2 = pEnumDSName.Next
    Loop
End Sub

Answer 2

您可以在地理处理器上使用ListFeatureClasses方法(以下显示了如何在C#中执行此操作)

IGeoProcessor gp = new GeoProcessorClass(); 

gp.SetEnvironmentValue("workspace", @"C:\temp"); 

IGpEnumList gpEnumList = gp.ListFeatureClasses("*", "Polygon", ""); 
string fc = gpEnumList.Next(); 
while (fc != "") 
{ 
//Do whatever
}